Powell's antiquated AOL account, which worked over a phone line in his office at the State Department, might have been more vulnerable to attack by hackers than the private email server the Clinton used during her tenure as secretary.

Powell said in a statement he viewed his use of private email to communicate with foreign leaders and senior U.S. officials as private conversations similar to phone calls. He said he was unaware of any requirement that those messages be preserved as government records, potentially subject to public release.